1. Field of the Invention
The present invention relates to a marker and a guide sheath system to be attached to an endoscopic treatment tool. This application claims priority on Japanese Patent Application No. 2007-171851 filed on Jun. 29, 2007, the disclosure of which is incorporated herein by reference.
2. Description of the Related Art
An operator performing an endoscopic biopsy of a peripheral lesion in a lung often locates a target site in a bronchiole. The bronchiole diameter is so small that a usual endoscope tip cannot reach the target site. In some cases, the bronchiole may be branched several times from the tip of the endoscope to the target site, and thus it is difficult to repeatedly make the treatment tool reach the target site after taking biopsy tissue samples at that site.
To address this problem, Japanese Unexamined Patent Application, First Publication No. 2004-154485 discloses a method for biopsy in which a guide sheath having a diameter smaller than that of the endoscope is inserted in a channel of the endoscope, projected from an endoscope tip to be held near a target site, and a treatment tool is inserted in the guide sheath for performing biopsy.
A targeted lesion is often very small. Even if a lesion is detected by using a ultrasonic probe or other instruments, it is difficult for an operator to determine how far the treatment tool such as forceps is to be advanced for performing biopsy after the removal of the ultrasonic probe. Merely several millimeters of misalignment may cause the treatment tool to miss the target site. A problem has currently arisen that it is only after the inspection is completed that the operator finds out whether or not proper tissue samples were taken. In addition, usually the tissue samples are taken five or six times at a site, the above-mentioned problem may occur more often. In fact, accuracy in such a biopsy is currently insufficient.
If the tip position of the treatment tool is observed at all times by X-ray radioscopy, the above problems may be avoided. However, the X-ray radioscopy may expose the patient to radiation in a large amount. Thus, it is a seriously invasive procedure for just an inspection.